Solved

how do I log inbound traffic with a cisco 1721

Posted on 2004-10-13
4
992 Views
Last Modified: 2012-05-05
We are getting an unusual amount of inbound traffic for about 7 hours per night and we would like to monitor where this traffic is coming from.  Is there a way to enable the 1721 to log the inbound traffic?
0
Comment
Question by:genekurtz
  • 2
4 Comments
 
LVL 79

Accepted Solution

by:
lrmoore earned 500 total points
ID: 12298115
You can enable netflow on the interfaces

interface serial 0/0
  ip route-cache flow

interface fast 0/0
  ip route-cache flow

Examining the flows will show you source/destination IP addresses and ports.
Exporting the flow to something like NTOP will give you a tremendous amount of information:
http://www.ntop.org

Or you can enable ip accounting on the serial interface. This will also give you a lot of information with "show ip account"
0
 
LVL 1

Expert Comment

by:whippy_bb
ID: 12304648
you can also set an access control list on the external interface:

router#
router#conf t
router(config)#access 100 permit tcp any any log
router(config)#access 100 permit udp any any log
router(config)#access 100 permit ip any any log
router(config)#int s0/0
router(config-int)#ip access group 100 in
router(config-int)#exit
router(config)#logging buffered
router(config)#buffer 4096
router(config)#exit
router#wr mem

you could then log back in and type "show log" to see the reslts.
If you really wanted to get special with it you could even restrict the time the access ist was active. Check Cisco's site for more in depth details.
Regards

Whippy



0
 
LVL 5

Expert Comment

by:AutoSponge
ID: 12328499
It's unclear from your statement if the data is also hitting the LAN or if the router is unable to route the traffic and is therefore dropping it.  If you're not sure either, try:

config t
int (LAN)
ip accounting output-packets

then perform a 'show ip accounting' before and after the window.  You'll be able to see if the traffic is being requested or sent to one of your LAN devices.  If not, the router is dropping it and you'll need something else... like a firewall would really help.
0
 
LVL 5

Expert Comment

by:AutoSponge
ID: 12328501
I just realized this was for a 1721 (I was thinking 2500).  Sorry for the FW comment.
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
How do I allow multiple VLANs internet access on a Cisco ASA 5505? 8 39
Router Question 12 56
Cisco Edge Routers for BGP 6 54
NAT/PAT unable to config correctly 7 17
In this tutorial I will show you with short command examples how to obtain a packet footprint of all traffic flowing thru your Juniper device running ScreenOS. I do not know the exact firmware requirement, but I think the fprofile command is availab…
Tired of waiting for your show or movie to load?  Are buffering issues a constant problem with your internet connection?  Check this article out to see if these simple adjustments are the solution for you.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

820 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question